Liquid-assisted femtosecond laser drilling of straight and three-dimensional microchannels in glass
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- Hwang, D., Choi, T. & Grigoropoulos, C. Appl. Phys. A (2004) 79: 605. doi:10.1007/s00339-004-2547-8
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Ultra-short-pulse lasers have proved to be effective tools for micromachining a wide range of materials. When the ultra-short laser pulse is focused inside the bulk of a transparent medium, nonlinear absorption occurs only near the focal volume that is subjected to high intensity. Three-dimensional structures can be fabricated inside transparent materials by taking advantage of this volumetric absorption. In this paper, femtosecond laser pulses were used to fabricate straight and bent through-channels. Drilling was initiated from the rear surface to preserve consistent absorption of the laser pulse. When the debris was not removed efficiently, variation of the channel diameter and occasional termination of the drilling process were observed. Machining in the presence of a liquid and additional use of ultrasonic wave agitation facilitated the debris ejection. The machined channels had diameters on the order of tens of microns, high aspect ratios, and good wall-surface quality.